Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H, W = map(int, input().split())
G = [list(input()) for _ in range(H)]
que = [[0,0]]
dist = [[-1]*W for _ in range(H)]
direction = [[0,1], [0,-1], [1,0], [-1,0]]

dist[0][0] = 0
while que:
  h, w = que.pop(0) 
  for dh, dw in direction:
    if h+dh <0 or h+dh >= H or w+dw <0 or w+dw >= W:
      continue
    if G[h+dh][w+dw] == '#':
      continue
    if dist[h+dh][w+dw] != -1:
      continue
    dist[h+dh][w+dw] = dist[h][w] +1 
    que.append([h+dh, w+dw])

if dist[H-1][W-1] == -1:
  print(-1)
else:
  num = 0
  for i in range(H):
    num += G[i].count('#')
  print(H*W-num-dist[H-1][W-1]-1)